Typically, when a new road is added to map data used in a navigation apparatus, a map production company edits road data by using map edit software and updates the map data partially or wholly based on the road data. Specifically, the map production company collects new road data by driving a specialized vehicle on the new road and then spends several months creating new map data based on the collected road data. Since it takes a lot of time to create the new map data, the new map data may be no longer new when it is used in the navigation apparatus.
A navigation apparatus disclosed in JP-6-88733A or JP-2006-125883A has a road learning function to learn a new road, whose data is not in ready-made map data, based on a movement trajectory of a vehicle from an exit point to a return point. The exit point is a point where the vehicle exits an existing road, whose data exists in the ready-made map data. The return point is a point where the vehicle returns to another existing road.
In general, a navigation apparatus provides no guidance on a direction to go at an intersection, when a route to a destination follows a road, where the vehicle runs, through the intersection. In other words, a navigation apparatus provides no guidance on the direction to go at an intersection, when the vehicle needs to continue straight through the intersection.
However, in a navigation apparatus having a road learning function, even when the vehicle needs to continue straight through a new intersection learned by the road learning function, guidance indicating that the vehicle needs to continue straight through the new intersection is provided at the new intersection. A user may feel unpleasant with such unnecessary guidance.